I like the idea of the boiled linseed oil but it was so sticky in places and so gummy to get up I'm afraid to use it again!! Is it possible it was applied wrong in the first place?
Very possible and/or a poor grade of Flax Oil with too many modern petroleum additives put in it to thin it down (aka make cheaper.) Real Flax Oil finishes (aka Linseed) are one of the best easy to apply finishes there are.
I am a staunch traditionalist and find most "modern finish" really crappy at best, especially for exterior use...As I enform clients all the time..."Modern finish are only modern...they are far from being better when compared to traditional finishes."
I would also note, you can forget ever doing an easy job of refinishing anything with modern plastic finish applied to it like poly, epoxies or the related.
I make all my own finishes and/or use only natural finishes, so never recommend...modern plastic finishes on wood or masonry ever. It is even more of an issue with exterior exposure. I would recommend Heritage Finishes
, which I have used for over 30 years. It is a blend of Tung Oil, Flax Oil, Beeswax, and Pine Rosin with a Citrus Oil thinner and UV stabilizer for the exterior grade material. I would note also these come from "food grade" resources with no additives, or moder petroleum distillates.
Many colleagues and project directors specify Waterlox
line of products. They have only high praise for the results and I have seen little issue over the years.
For pigments, you can make your own. For example a nice gray is found in Vinegar and Steel Wool. For other pigments to add to your desired effect, Heritage Finishes sells them but my first choice for my pigments (if I don't make them myself) is The Real Milk Paint Company
. Diawyne is the owner, and a wonderful resource on traditional finishes...
Hope this helps.